Shelf



FIG. 1 is a perspective view of a shelf showing my new design;

FIG. 2 is an enlarged fragmentary perspective view of the inside wall of the right vertical support;

FIG. 3 is a perspective view of the shelf assembly in full lines, with the broken lines showing matter for illustrative purposes only and forming no part of the claimed design;

FIG. 4 is a top plan view of the new design;

FIG. 5 is a front elevational view thereof, a view of the back being a mirror image thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a left side elevational view thereof, a view of the right side being a mirror image thereof. 

The ornamental design for a shelf, as shown and described. 